Why can't I activate Windows?

If you receive a message saying you cannot activate Windows, for example, "Unable to activate Windows It looks like the hardware on this device has changed. Make sure you're connected to the Internet and try again later. (0x0ea000a)," then follow the steps below.

1. Open Powershell as administrator

2. Enter the command: slmgr -ipk <Your product key here>

3. Then enter this command: slmgr -ato